“Dynamic Regulation Mode” is widely used in switching converters to prevent damage to a load due to an over output voltage which exceeds a defined threshold. In dynamic regulation mode, a rectifier in the switching converter is turned on to lower the output voltage. Thus, an inductor current flowing through the rectifier decreases gradually in a positive direction at first, and then further decreases in a negative direction until a negative current limit of the rectifier is reached, at which moment, the rectifier is turned off for a fixed time period. Afterwards, a new cycle repeats.
As the off time of the rectifier is fixed, and the slope of the inductor current varies as a function of the difference between an input voltage applied to the switching converter and the output voltage during this off time, a large variation in the output current of the switching converter occurs when there is a variation in the input voltage or the output voltage.